1. Field of the Technology
The present technology relates to a toner cartridge used so as to be detachably attached to an image forming apparatus such as a laser printer and a multi-functional peripheral and an image forming apparatus including the same.
2. Description of the Related Art
An image forming apparatus using an electrostatic electrophotographic system generally includes respective steps of charging, exposure, developing, transferring, cleaning, charge removing, and fixing. At a step of forming an image, for example, a surface of a photoreceptor, which is rotationally driven, is uniformly charged by a charging device and the charged surface of the photoreceptor is irradiated with laser beam by an exposure device, so that an electrostatic latent image is formed. Subsequently, the electrostatic latent image on the photoreceptor is developed by a developing device, so that a toner image is formed on the surface of the photoreceptor. The toner image on the photoreceptor is transferred onto a printing sheet of paper by a transfer device and thereafter the toner image is fixed on the printing sheet of paper by being heated by a fixing device. Further, residual toner which remains on the surface of the photoreceptor after transferring is removed by a cleaning device and collected in a predetermined collecting section while the surface of the photoreceptor after being cleaned has residual electric charge removed by a charge removing device to prepare for next image formation.
As developer with which an electrostatic latent image on a photoreceptor is developed, one-component developer composed of only toner or two-component developer composed of toner and carrier is used. The one-component developer does not need an agitating mechanism for mixing toner and carrier uniformly and the like due to no use of carrier, and thus has an advantage such that a configuration of a developing device is simplified, however, has a disadvantage such that a charging amount of toner is hard to be stabilized due to no use of carrier, and the like. The two-component developer needs the agitating mechanism for mixing toner and carrier uniformly and the like and thus has a disadvantage such that a developing device is complicated, however, is often used for an image forming apparatus for high-speed printing and a color image forming apparatus because of having excellent stability of a charging amount and adaptability to high-speed printing.
In the case of performing image formation using the two-component developer, toner contained in a toner cartridge is automatically supplied to a developing device from a discharging port after toner inside the developing device is consumed, and thereby image formation is able to be performed successively. The toner cartridge is detachably attached to an apparatus main body of an image forming apparatus and replaced with a new toner cartridge when the contained toner is consumed due to supply to the developing device.
As such a toner cartridge, one shown in FIG. 10 has been proposed. FIG. 10 is a diagram showing a configuration of a toner cartridge 300 according to a first conventional technology. The toner cartridge 300 according to the first conventional technology shown in FIG. 10 includes a toner container 301 having a toner containing space 306 in which toner is contained, an auger screw 303 and a shutter 305. In the toner container 301, a toner discharging port 302a for discharging the toner is formed at a bottom wall 301a in one longitudinal end side of a container main body which is formed in a cylindrical shape. This toner discharging port 302a is opened and closed with the shutter 305. Moreover, the auger screw 303 is disposed inside the toner containing space 306 of the toner container 301 and has a rotation shaft 303a supported rotatably on end walls 302 which shut both opening ends of the container main body and a spiral blade 303b that encircles the rotation shaft 303a and is fixed by the rotation shaft 303a. The auger screw 303 conveys the toner contained in the toner container 301 toward the toner discharging port 302a by rotation of the spiral blade 303b associated with rotation of the rotation shaft 303a. 
When being attached to the apparatus main body of the image forming apparatus, the toner cartridge 300 according to the first conventional technology is able to replenish the toner to the developing device by discharging the toner conveyed by the auger screw 303 from the toner discharging port 302a. 
However, in the toner cartridge 300 according to the first conventional technology, toner existing on an upper side of the auger screw 303 also flows into the toner discharging port 302a together with the toner conveyed in an axial direction by the auger screw 303, so that there is a problem that a quantity of the toner discharged from the toner discharging port 302a is not stabilized.
As a toner cartridge for solving such a problem, one shown in FIG. 11 has been proposed. FIG. 11 is a diagram showing a configuration of a toner cartridge 400 according to a second conventional technology. The toner cartridge 400 according to the second conventional technology shown in FIG. 11 includes a toner container 401 having a toner containing space 406 in which toner is contained, a toner discharging section 404 which is disposed in a vicinity of a toner discharging port 402a formed at a bottom wall 401a in one longitudinal end side of the toner container 401 and has a configuration of extending from the toner container 401, an auger screw 403 and a shutter 405. The toner discharging port 402a arranged in the toner discharging section 404 is opened and closed with the shutter 405. Moreover, the auger screw 403 is disposed inside the toner containing space 406 of the toner container 401 and inside the toner discharging section 404, and has a rotation shaft 403a supported rotatably on end walls 402 which shut both opening ends of the toner container 401 and a spiral blade 403b that encircles the rotation shaft 403a and is fixed by the rotation shaft 403a. The auger screw 403 conveys toner contained in the toner container 401 toward the toner discharging port 402a via the toner discharging section 404 by rotation of the spiral blade 403b associated with rotation of the rotation shaft 403a. 
When being attached to an apparatus main body of an image forming apparatus, the toner cartridge 400 according to the second conventional technology is able to replenish toner to a developing device by discharging the toner conveyed by the auger screw 403 from the toner discharging port 402a arranged in the toner discharging section 404. Furthermore, since the toner discharging port 402a from which toner is discharged is arranged in the toner discharging section 404 which has small toner containing space capacity, the toner cartridge 400 according to the second conventional technology is able to suppress that toner existing on an upper side of the auger screw 403 flows into the toner discharging port 402a, making it possible to stabilize a quantity of the toner discharged from the toner discharging port 402a. 
In addition, as one similar to the toner cartridge 400 according to the second conventional technology, for example, one described in Japanese Unexamined Patent Publication JP-A 2000-214667 has been proposed.
In a case where the toner cartridge 400 according to the second conventional technology shown in FIG. 11 is kept in a state of being upright with a toner discharging port 402a side facing downward, toner in the toner container 401 comes down by its own weight with lapse of time and toner density near the toner discharging port 402a becomes high. As a result of this, a problem is caused that the toner near the toner discharging port 402a aggregates and further becomes a lump to shut the toner discharging port 402a. Note that, also depending on vibrations and a loading situation at a time of transport of the toner cartridge 400, it may occur that the toner density near the toner discharging port 402a becomes high to cause an aggregation.
In the case of attaching the toner cartridge 400 whose toner discharging port 402a is shut by such an aggregation or a lump of the toner to the apparatus main body of the image forming apparatus, the toner is difficult to be discharged from the toner cartridge 400, and it may occur that judgment of exhaustion of toner is made in an apparatus main body side even though a large quantity of toner remains inside the toner cartridge 400. Moreover, failure that the aggregation or the lump of the toner near the toner discharging port 402a is compressed and hardened by pressure of the auger screw 403, resulting that the auger screw 403 is locked, may occur as well.
Moreover, the toner cartridge described in JP-A 2000-214667 is configured to reduce pressure on toner in a toner discharging port side by an auger screw at a time of toner conveyance for preventing aggregating of toner by cutting a part of a spiral blade of the auger screw in the toner discharging port side. However, the toner cartridge described in JP-A 2000-214667 is not able to cope with aggregating of toner which occurs in the case of being kept in the state of being upright with the toner discharging port side facing downward.